Many petroleum refining processes are known for the recovery of hydrocarbon material from solid and semi-solid petroleum resources such as asphalt, tar, pitch and many other substances, where the substance is processed or reprocessed in the refinery into a more valuable sellable product, and a residue meeting environmental regulatory agency requirements for disposal in solid waste landfills. These valuable solid or semi-solid substances, however, may present special handling problems in preparation for recovery of usable hydrocarbon material in a petroleum refinery.
While deposits of solid or semi-solid petroleum resources occur naturally in the earth's crust, recoverable resources of asphalt, tar and pitch may also result from man-made deposits such as recovery from deposits of previously discarded distillation residue, or recovery of road asphalt, etc. In any of the above-mentioned solid or semi-solid petroleum resource deposits, there is likely to be found solid debris including rocks of various sizes, discarded metal or glass objects, etc., and these debris contained in the petroleum substance cause damage to refinery equipment if the debris is not removed prior to feeding the petroleum substance into the refinery equipment.
Attempts to separate debris from pitch by heating the material to be recovered using a heat exchange surface and then screening the debris have met with little success because the screen rapidly becomes plugged with sticky material, the heat exchange equipment also becomes plugged and fouls, and the rotating equipment used to move the pitch jams on the debris contained in the pitch.
Accordingly, it is an object of this invention to improve the apparatus used for removing debris contained in pitch to be processed in a refinery.
Another object of this invention is to operate a screening apparatus for removing debris contained in pitch in a manner that prevents plugging of the screen with pitch.
A further object is to melt the pitch without the pitch contacting a solid heat exchange surface.
A still further object of this invention is to dislodge debris from solid pitch.
Additional objects, advantages and novel features of the invention will become apparent to those skilled in the art from the following detailed description of the invention, the appended claims and the drawing which is briefly described as follows: